<?php 
class Fac
{
	static private $instance;
	public function __construct()
	{

	}

	//用于实例化缓存对象
	public static function instance()
	{
		if(!self::$instance)
		{
			$config = require 'config.php';
			$driver = ucfirst($config['driver']);
			$file = 'Cache/'.$driver.'.php';
			require_once $file;
			
			return self::$instance = new $driver;
		}
		return self::$instance;

	}
}